Reaction Dynamics of Excited States of Transition Metal Atoms

实验研究了气相金属原子反应的激发态动力学。根据实验结果，得到了势能面的详细信息。采用交叉束技术实现了单次碰撞条件，避免了制备电子态的碰撞混合，通过激光蒸发产生金属原子，并以金属原子束的形式发射。该光束与分子束以直角交叉，并且通过激光诱导荧光（LIF）和/或化学发光技术检测交叉区域中的反应产物。在本项目期间，研究了以下反应：（^2P_<1/2，3/2>）+O_2（S^3 <$^-_g）→AlO（X^2 <$^+）+O（^3P_J）（1）Y（^2D_<3/2，5/2>）+O_2（X^3 ^-_g）→YO（X^2 Δ ^+，A^2 Δ_<3/2，5/2>，A^2 Δ_<1/2，（2）选择性地产生了两个自旋轨道态，并确定了AlO的振转态分布。采用真空紫外激光诱导荧光技术测量了O原子三种自旋轨道态的布居。对于Al的两种自旋-轨道态，振动-转动态几乎呈现统计分布。这一结果表明反应通过长寿命的中间体进行。另一方面，O的自旋轨道态与统计预期不一致。通过对YO（A^2 <$_1/2，3/2>）的化学发光光谱的分析，确定了YO（A^2 <$_1/2，3/2>）的能量分配。振动旋转状态分布再次几乎是统计的，并提出了一个复杂的机制。分析了O原子的多普勒分布，以估计基态YO与激发态YO的相对分支比。结果表明，在反应（2）中发生了两个以上的途径。

The dynamics of the excited states has been studied experimentally for the reactions involving gas-phase metal atoms. Based on the experimental results, the detail information about potential energy surfaces has been obtained. The crossed-beam technique has been used to achieve the single collision condition, which avoids collisional mixing of electronic states prepared.Metal atoms were generated by the laser vaporization and issued as a metal atomic beam. This beam was crossed with a molecular beam at right angle and reaction products in the crossing region were detected by laser-induced fluorescence (LIF) and/or chemiluminescence techniques. During the term of this project, the following reactions have been studied.Al(^2P_<1/2,3/2>)+O_2(S^3Σ^-_g)→AlO(X^2Σ^+)+O(^3P_J) (1)Y(^2D_<3/2,5/2>)+O_2(X^3Σ^-_g)→YO(X^2Σ^+,A^2Δ_<3/2,5/2>,A^2Π_<1/2,3/2>)+O(^3P_J) (2)Two spin-orbit states were selectively generated and vib-rotational state distributions of AlO were determined for these initial staets. The vacuum ultraviolet LIF technique was employed to determine the populations of three spin-orbit states of the O atom. For both spin-orbit states of Al, the vib-rotational states show almost statistical distribution. This result suggests that the reaction proceeds via a long-lived intermediate. On the other hand, the spin-orbit states of O do not agree with the statistical expectation. This interaction among different spin-orbit states likely to occur at entrance and exit channels of the intermidiate.Chemiluminescence spectra of YO(A^2Π_<1/2,3/2>) were analyzed to determine the energy partition into this product. The vib-rotational state distributions are again almost statistical and a complex mechanism is suggested. The Doppler profiles of the O atom were analyzed to estimate relative branching ratios for YO in the ground state vs. YO in the excited states. The results suggest that more than two pathways take place in reaction (2).